Permanent color gaseous conduction tube



Patented Oct. 23, 1934 PERMANENT COLOR GASEOUS CONDUCTION TUBE Richard E. Miesse, Chicago, Ill., assignor, by

mesne assignments, to General Scientific Corporation,. Chicago, Ill., a corporation No Drawing. Application March 10, 1930, Serial No. 434,821

2 Claims.

My invention relates to gaseous conduction tubes such as are used for advertising signs and the like-and has for its principal purpose the provision of means for maintaining a permanent 5 color in such tubes.

Gaseous conduction tubes such as are used for advertising purposes are made by exhausting the glass tubing having the proper electrodes therein and filling them with different gases depending on the colors desired.

As an example, neon gas is used for a red color, helium gas gives a brownish yellow color, and, in the past, the blue color has been produced by adding a small amount of mercury to neon gas.

When mercury is thus used, its spectrum is much stronger than that of neon, only a strong blue light can be seen and practically none of the red color present due to the neon and little of the greenish tinge of mercury could be discerned in clear glass tubing. The neon thus introduced into a tube containing mercury is said to carry the current resulting in ionization of the mercury vapor in the tube producing strong radiation of the characteristic blue light of mercury vapor.

This type of tube works very well as long as the surrounding temperature of the air is sufilciently high to allow a sufficient pressure of mercury vapor. When the temperature drops to 32 degrees F. or lower, this is no longer true, and there is not suflicient mercury vapor present to give the characteristic mercury spectrum in full strength. The red neon color again comes into prominence and gives a resulting color which is weak and very unsatisfactory producing a mottled red and blue 35 effect.

Different workers in the art have tried various methods of overcoming this fault such as by using helium instead of neon as the gaseous conductor. Helium has the highest specific heat of all elements, and it was expected that helium would thus heat the mercury sufilciently to cause the continual evolution of mercury vapor regardless of the surrounding air temperature. Such experiments show. that helium was not as satisfactory as neon as a gaseous conductor.

Through my experiments I have found that a new phenomenon enters when the permanent blue tube is to be made which will operate satisfactorily at any ordinary temperature. It is believed that the gas used as the conductor receives practically all of the electrical energy and that it will dispense some of this energy to the mercury in such amounts as the ratio of the atomic weights of the gas and the mercury. Conflning the gas used to PATENT OFFICE one which belongs to the monatomic group, we

have the following:

Gas

It will be assumed from the above table that krypton and xenon have the highest atomic weights of all these gases and thus are the best to use.

Since the atomic weight of mercury is each other. are as follows:

Some of these mixtures (by volume) Percent Percent Nmn I 99 NPO'H 99 Krypton 1 Xenon 1 Neon 98 N 98 Krypton 2 Xenon 2 Neon 97 Neon 97 Krypton 3 Xenon 3 Neon 96 N n 96 Krypton 4 Xenon Nmn 95 Noon 95 Krypton 6 Xenon 5 Norm 94 NPR" 94 Krypton 6 Xenon 6 Neon 93 Noon 93 Krypton 7 Xenon 7 Neon 92 Narm 92 Krypton 8 Xenon 8 Neon. 91 Neon 91 Krypton 9 Xenon 9 Norm 90 Neon 90 Krypton 10 Xenon 10 It appears from my experiments that the 10% mixtures work almost as well as the pure gas alone with the mercury over the temperature range I had available. Of course, as hereinbefore stated, the amount of energy given to the mercury depends upon theratio of the atomic weights of the mercury and the gas, and hence, if only 1% of krypton or xenon were mixed with 99% of neon, there would only be of the energy given to the mercury that would be given in case 10% krypton of xenon were. mixed with 90% neon. Thus it can be readily seen that the 10% mixture would keep the tube a permanent blue color at temperatures much lower than would be the case if a 1% mixture were used.

Thus, because of the high cost and rarity of the krypton and xenon, it is my intention to use percentages of these gases with other cheaper monatomic gases according to the necessity imposed by the climatic conditions where the tube is to be operated.

As an example, I might find that the temperature at New Orleans never goes below 30- degrees F. in which case I would be able to use from .5% to 3% krypton or xenon with another monatomic gas. In Chicago where the temperatures go as low as 15 degrees F., I might find that 10% of krypton or xenon would have to be added to another monatomic gas. In extremely cold areas such as Winnipeg, Canada, the percentage would be increased to 15 or 20% of krypton or xenon added to another monatomic gas.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A gaseous conduction tube having therein mercury vapor and a monatomic gas incapable in themselves of causing the tube when excited to give the characteristic blue light radiation of mercury when exposed to temperatures below about 20 F., said tube having therein in addition a quantity of one of the heavy monatomic gases whose atomic weight is greater than that of argon for maintaining the blue radiation from the tube when so exposed, the percentage of said heavy monatomic gas up to a substantially critical value determining the minimum temperature at which said tube will give the characteristic mercury radiation, and said heavy monatomic gas energizing said mercury for the purposes described.

2. A gaseous conduction tube having therein mercury vapor and a monatomic gas incapable in themselves of causing the tube when excited to give the characteristic blue light radiation of mercury when exposed to temperatures below about 20 F., said tube having therein in addition a quantity of one of the heavy monatomic gases whose atomic weight is greater than that of argon for maintaining the blue radiation from the tube when so exposed.

RICHARD E. MIESSE. 

